Backup Power Supply Device for a Storage Device

1. A storage device comprising: a disk driving device for storing data that are received from an information processing apparatus; a cache memory for temporarily retaining data to be stored in the disk driving device; a backup power source for backing up individual units of the storage device including the disk driving device and the cache memory; a power failure detecting unit for checking a status of power supply from a power source; a backup power supply control unit for distributing output power of the backup power source to the individual units of the storage device including the disk driving device and the cache memory in a first period that starts after detection of a power failure by the power failure detecting unit, and for supplying the cache memory with power that has been distributed to units excluding the cache memory after a lapse of the first period; a data accepting unit for accepting data from the information processing apparatus and writing the accepted data to the cache memory; and a data transfer unit for transferring data stored in the cache memory to the disk driving device, wherein the power failure detecting unit is provided in each of the data accepting unit and the data transfer unit, and the power failure detecting units detect a power failure by checking statuses of power supply from the power source in the data accepting unit and the data transfer unit, respectively, and communicating check results to each other.

2. The storage device according to claim 1 , wherein the data accepting unit continues an operation of accepting data from the information processing apparatus and writing the accepted data to the cache memory until a lapse of a second period that starts after the detection of the power failure by the power failure detecting units and that is shorter than the first period.

3. The storage device according to claim 2 , wherein the backup power supply control unit distributes the output power of the backup power source only to devices that are necessary to transfer the data from the cache memory to the disk driving device in a period from the lapse of the second period to the lapse of the first period.

4. The storage device according to claim 3 , further comprising a status monitoring unit for monitoring statuses of the disk driving device and/or the cache memory, wherein the backup power supply control unit supplies the cache memory with power that has been distributed to units excluding the cache memory even before the lapse of the first period if the status monitoring unit judges on the basis of a monitoring result that writing to the disk driving device of the data transferred from the cache memory will not be completed in the period from the lapse of the second period to the lapse of the first period.

5. A storage device comprising: a disk driving device for storing data that are received from an information processing apparatus; a cache memory for temporarily retaining data to be stored in the disk driving device; a backup power source for backing up individual units of the storage device including the disk driving device and the cache memory; power failure detecting units for checking a status of power supply from a power source; a backup power supply control unit for distributing output power of the backup power source to the individual units of the storage device including the disk driving device and the cache memory in a first period that starts after detection of a power failure by the power failure detecting unit, and for supplying the cache memory with power that has been distributed to units excluding the cache memory after a lapse of the first period; a status monitoring unit for monitoring statuses of the disk driving device and/or the cache memory; a dedicated power line for supplying output power of the backup power source to only the cache memory, the dedicated power line comprising a switching unit for always establishing an electrical connection between the backup power source and the cache memory; a data accepting unit for accepting data from the information processing apparatus and writing the accepted data to the cache memory; and a data transfer unit for transferring data stored in the cache memory to the disk driving device, wherein the power failure detecting units are provided in the data accepting unit and the data transfer unit, respectively, and detect a power failure by checking statuses of power supply from the power source in the data accepting unit and the data transfer unit, respectively, and communicating check results to each other, and the data accepting unit continues an operation of accepting data from the information processing apparatus and writing the accepted data to the cache memory until a lapse of a second period that starts after the detection of the power failure by the power failure detecting units and that is shorter than the first period; wherein the backup power supply control unit distributes the output power of the backup power source only to devices that are necessary to transfer the data from the cache memory to the disk driving device in a period from the lapse of the second period to the lapse of the first period; and wherein the backup power supply control unit supplies the cache memory with power that has been distributed to units excluding the cache memory even before the lapse of the first period if the status monitoring unit judges on the basis of a monitoring result that writing to the disk driving device of the data transferred from the cache memory will not be completed in the period from the lapse of the second period to the lapse of the first period.